Simple homemade Raman spectrometer / microscope

In summary, the conversation discusses the design and components of a Raman spectrometer that can also function as a microscope. It uses a 532nm laser, an infinity-corrected microscope objective, a 200 lines/mm diffraction grating, and a confocal lens pinhole setup. The camera used is a 5 megapixel camera focused at infinity, and the diffraction grating splits wavelengths towards the camera at a 80 degree angle. The confocal lens pinhole setup can be moved aside to allow for a full microscope image. The conversation also includes a list of the components being used and a discussion about finding the right parts. The website Photonics Spectra is mentioned as a potential resource.
  • #1
carmatic
92
1
TL;DR Summary
Please help me design and find the right parts for my Raman microscope.
SmartSelect_20201123-180923_WPS Office.jpg

Hello everyone, I am attempting to make a Raman spectrometer which can double as a microscope. It uses a 532nm laser for excitation, an infinity-corrected microscope objective to collimate the light, a 200 lines/mm diffraction grating, and a confocal lens pinhole setup. A 5 megapixel camera , with the lens focused at infinity for receiving collimated light, is at 90 degrees relative to the direction at which the light hits the diffraction grating.
The diffraction grating splits the wavelengths below 532nm towards the camera when the face normal is around 80 degrees relative to the incoming light, and reflects a full microscopic image when rotated to 45 degrees.

The focal point from the laser light appears as a bright dot in the middle of the microscopic image.
The confocal lens pinhole setup, in the inset, is used to isolate the light from this bright dot to be diffracted and separated into the individual wavelengths. It can be moved aside to allow the full image from the microscope objective to pass when a microscope image is desired.

Can someone verify that this is a correct design and the parts are okay?
Thanks in advance

Here are the numbered parts:
1. Arducam Raspberry Pi 5mp camera https://www.amazon.com/dp/B012ETE75I/?tag=pfamazon01-20

2. 1200 Grooves, 12.7mm Square, 1000nm Ruled Diffraction Grating https://www.edmundoptics.com/p/1200-grooves-127mm-square-1000nm-ruled-diffraction-grating/5257/

3. 12.5mm Diameter 45°, Green Dichroic Filter https://www.edmundoptics.com/p/1200-grooves-127mm-square-1000nm-ruled-diffraction-grating/5257/

4. 12.7mm Dia. x 19.1mm FL, VIS 0° Coated, Achromatic Lens https://www.edmundoptics.com/p/127mm-dia-x-191mm-fl-vis-0deg-coated-achromatic-lens/10223/

5. 532nm, 12.5mm Diameter, OD 4.0 Notch Filter https://www.edmundoptics.com/p/532nm-125mm-diameter-od-4-notch-filter/21647/

6. Olympus PLN 4X Objective https://www.edmundoptics.com/p/olympus-pln-4x-objective/29221/

Laser https://www.amazon.com/dp/B018Z7ZLYY/?tag=pfamazon01-20
 
Last edited:
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  • #2
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I have access to a laser cutter and I have also built a provisional enclosure for the parts. I already own most of the parts except the confocal pinhole setup. I tried it out with a plastic bottle; The main plastic bottle body gives a broad response from green to red, while the bottle cap has a weak red signal in addition to the green Rayleigh scattering.

The camera seems to be picking up some invisible radiation which shows up as purple in the images, I would assume that it is unwanted infrared light from the laser?
 
  • #3
carmatic said:
Summary:: ... and find the right parts
Photonics Spectra may be a good place to find parts.
Here's their web site: https://www.photonics.com/; Check out their buyers guide.
 

1. What materials do I need to make a simple homemade Raman spectrometer/microscope?

To make a simple homemade Raman spectrometer/microscope, you will need a laser, a microscope, a diffraction grating, a detector, and a sample holder. You may also need additional materials such as lenses, filters, and mirrors depending on the design of your spectrometer.

2. How does a Raman spectrometer/microscope work?

A Raman spectrometer/microscope works by shining a laser onto a sample and measuring the scattered light. The scattered light contains information about the molecular vibrations of the sample, which can be used to identify the chemical composition of the sample.

3. Can I use a regular microscope for a homemade Raman spectrometer/microscope?

Yes, you can use a regular microscope for a homemade Raman spectrometer/microscope. However, you may need to make some modifications to the microscope, such as adding a laser and a detector, to make it suitable for Raman spectroscopy.

4. How accurate and sensitive is a homemade Raman spectrometer/microscope?

The accuracy and sensitivity of a homemade Raman spectrometer/microscope will depend on the quality of the materials used and the design of the spectrometer. With proper calibration and optimization, a homemade Raman spectrometer/microscope can achieve similar accuracy and sensitivity as commercial instruments.

5. Are there any safety precautions I should take when using a homemade Raman spectrometer/microscope?

Yes, it is important to take safety precautions when using a homemade Raman spectrometer/microscope. This includes wearing appropriate protective gear, such as safety glasses, and following proper laser safety protocols. It is also important to properly dispose of any hazardous materials used in the spectrometer.

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